Q: A classroom's climate control system brings in $$500\ \mathrm{m}^3 of $$air per minute at $$10\ ^\circ\mathrm{C}. If $$the air has a density of $$1.29\ \mathrm{kg/m}^3$$ and a specific heat of $$721\ \mathrm{J/kg\cdot ^\circ C}$$, what is the rate of heat transfer required to warm the air to $$20\ ^\circ\mathrm{C}$$?

$$7.75 \times 10^5$\ \mathrm{W}$$

Question 1

Which of the following statements best describes the zeroth law of thermodynamics?

Accepted Answer

If two systems are each in thermal equilibrium with a third system, then they are in thermal equilibrium with each other.

Question 2

A 1.1 kg iron horseshoe at $$550\ ^\circ\mathrm{C} is $$dropped into 15 kg of water at $$20\ ^\circ\mathrm{C}. If $$the specific heat of iron is $$450\ \mathrm{J/kg\cdot ^\circ C}$$ and that of water is $$4186\ \mathrm{J/kg\cdot ^\circ C}$$, what is the final equilibrium temperature, $$T_f$$, assuming no heat loss to the environment?

Accepted Answer

$$T_f \approx 36\ ^\circ\mathrm{C}$$

Question 3

Which equation correctly relates the amount of heat $$Q$$ required to change the temperature of a mass $$m of a $$substance with specific heat $$c by$$ $$\Delta T$$?

Accepted Answer

$$Q = m c \Delta T$$

Question 4

A metal rod of length $$L$$ and cross-sectional area $$A$$ has its ends maintained at temperatures $$T_1$$ and $$T_2$$ ($$T_1$$ \u003e $$T_2). $$The rate of heat transfer by conduction through the rod is given by:

Accepted Answer

$$H = -kA \dfrac{\Delta T}{L}$$

Question 5

Which of the following is the dominant mode of heat transfer in a vacuum?

Accepted Answer

Radiation

Question 6

A lake with a surface area of $$1.5 	imes 10^6$\ \mathrm{m}^2$$ and depth $$8.0\ \mathrm{m}$$ has a surface temperature of $$30\ ^\circ\mathrm{C}$$ and a bottom temperature of $$4\ ^\circ\mathrm{C}. If $$the thermal conductivity of water is $$0.61\ \mathrm{W/m\cdot K}$$, what is the rate of heat conduction through the lake?

Accepted Answer

$$H = 30\ \mathrm{MW}$$

Question 7

Which of the following best explains why convection is generally faster than conduction in fluids?

Accepted Answer

Convection involves bulk movement of fluid, rapidly transporting heat.

Question 8

Which property of a material most directly affects its rate of heat transfer by conduction?

Accepted Answer

Thermal conductivity ($$k)$$

Question 9

A student wants to convert a temperature of $$25\ ^\circ\mathrm{C} to $$Fahrenheit. Which formula should they use?

Accepted Answer

$$T_F = \dfrac{9}{5} T_C + 32$$

Question 10

Which of the following statements about thermal equilibrium is correct?

Accepted Answer

Two objects in thermal equilibrium have no net heat flow between them.

Question 11

A classroom's climate control system brings in $$500\ \mathrm{m}^3 of $$air per minute at $$10\ ^\circ\mathrm{C}. If $$the air has a density of $$1.29\ \mathrm{kg/m}^3$$ and a specific heat of $$721\ \mathrm{J/kg\cdot ^\circ C}$$, what is the rate of heat transfer required to warm the air to $$20\ ^\circ\mathrm{C}$$?

Accepted Answer

$$7.75 	imes 10^5$\ \mathrm{W}$$

Question 12

Which of the following is true about the relationship between temperature and the average kinetic energy of particles in a substance?

Accepted Answer

Temperature is directly proportional to the average kinetic energy of the particles.

Question 13

Which of the following is the correct Stefan-Boltzmann law for the power radiated by a blackbody?

Accepted Answer

$$P = \sigma A T^4$

Question 14

A thermometer is placed in thermal contact with an object. What does it measure?

Accepted Answer

The temperature of the object once thermal equilibrium is reached.

Question 15

Which of the following is NOT a method of heat transfer?

Accepted Answer

Diffusion

Question 16

If you want to keep your coffee hot for as long as possible, which property of the mug should be maximized?

Accepted Answer

Low thermal conductivity

Question 17

Which of the following temperature scales has an absolute zero at $$0$$?

Accepted Answer

Kelvin

Question 18

Which of the following best describes why large bodies of water moderate the climate of nearby land?

Accepted Answer

Water has a high specific heat, so it absorbs and releases heat slowly.

Question 19

Which of the following is the correct formula for converting Celsius to Kelvin?

Accepted Answer

$$T_K = T_C + 273.15$$

Temperature and Heat: Fundamentals and Thermodynamics

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